At this point, I assume, you have picked a website builder and went through the beginner's tutorials (if these are not enough, there are lots of tutorials -- videos and articles -- available; just search for the name of your website builder and terms such as tutorial, getting started, introduction, beginner's guide, etc, e.g.: weebly beginner's tutorial).

Set up a dedicated email address
I suspect you already have an email address (possibly, more than one). If you only have a personal email address, create a new email account dedicated to your small business, so you can keep all of your business communication separate from your personal life. Just don't create it at your Internet Service Provider (ISP), such as Comcast, AT&T, Verizon, Cox, etc. Using an ISP-specific email addresses (whether personal, or group, or business) is never a good idea because you may need to switch to a different ISP and what would you do then? Migrate all your messages? Send new email address to your friends? Modify all your online profiles (at online stores, etc)? You can do this, but why deal with such hassle when you can get a fully functional email box at Google (GMail) for free? If you don't like Google's interface, you can forward all incoming messages to any other address (including your ISP's), so if you change your ISP, then you will just need to update your GMail message forwarding settings. [Note: At the time of writing, GMail was the only email provider that allowed you to forward incoming messages to external -- i.e. non-GMail -- accounts.] To summarize:

Use GMail.

Create a separate GMail account for your business (if you already have a Google account, you can link it to your existing Google profile).

Give your small business GMail account a meaningful name (ideally, it should be named after your business, e.g. myverysmallbusiness@gmail.com or myverysmallbusiness.owner@gmail.com).

Forward messages from your small business Gmail account to the one that you prefer (in case you have more than one email accounts).

Create a website
When you create a website, give it a meaningful title and address. The address will be temporary, until you're ready to publish it under your own domain name, but it can be helpful if addresses match. For example, if your custom domain name is myverysmallbusiness.com, then, assuming you create your website using Weebly, set the temporary address to myverysmallbusiness.weebly.com. The website title should reflect the name or the nature of your business. In my example, a reasonable title would be My Very Small Business. You can also include keywords that you may expect customers to use when they perform searches or append a location (if you operate locally), such as My Very Small Business: Gadgets and Gizmos in New York City, NY (this may help your website get better ranking). Just don't make the title too long.

Pick a website template
When picking a website template you need to think about aesthetics (it should look nice), performance (it must load fast), and function (it must support the layout and navigation needs). Here are a few rules of thumb:

Less is more. Try picking a template with fewer elements. It may be easier to customize and tweak than a more complex template.

Use bigger font. If the website builder or specific template does not allow font customization, make sure that the font size is big enough. With population aging, bigger fonts will make your site more pleasing to more viewers.

No splash page. Your website should launch at the home page with useful information, not a useless animation, invitation to click the only link, or similar silliness.

Keep it quiet. Interaction with your website should be absolutely quiet. This means no "cool" sounds when user clicks links, flips pages, no greeting audio on the home page, et.

No autoplay. If you decide to embed video or audio, make sure it does not start to play automatically (the user must click the Play button to get it going).

If you see a website (maybe competitor's or unrelated) which design you really like, do not copy it. It's good to incorporate other people's ideas, but it's bad to make exact replicas (and it can be illegal, too).

Website structure
At the very least, your website must have the following pages:

Home: This is your introduction page. Use it to briefly describe your business and offer the information that would be useful to a potential customer. Don't make it too wordy.

Contact: Here you specify all the ways a customer can reach you: phone, fax, email, address. If you are operating a brick and mortar shop, include a map with a link to driving directions.

Portfolio*: If you have pictures to demonstrate your previous works or items on sale, put their photos on a separate page. This is a personal preference, but I would not use a slide show to display your work; I would use a photo gallery instead. The photo gallery will allow your customers to find what they look for quicker. If you have a lot of photos you want to share or if you continuously update them, I would keep a dozen or so of your best works on the website and store the rest at a different photo hosting site, such as Flickr or Picasa; then add a link to your web albums at the photo hosting site.
* This is not the best name for the page, so try using something else that fits better for your purpose, such as Gallery, Photos, etc.

Services: If you offer fixed-price services, add a page that lists them. If you offer promotions or coupons, include this information as well (it can go to a separate page).

Resources: If you have links to useful information that you think can be helpful to your customers (even if they never contact you), include them in this page. Be a good citizen regardless of business impact (although, this can indirectly help you, too).

About: Use this page to offer a more detailed overview of your business. Specify when your business has been lunched and where it operates. List the terms of your workers compensation insurance. Include your business or permit license number. Use links to sources that customers can use to verify the information.

Web graphics
I'd recommend that at the first draft of your small business website, you do not put any pictures on the web pages (unless they are part of the template). Try to make it look nice without any graphics. Then add graphics but try to limit it to one primary graphics file per page (not counting smaller images, such as thumbnails or logos). Of course, you can break this rule if you have a valid reason.

Where to get graphics?
It is best to use your own graphics files. If you operate a brick and mortar business, you can take a photo of your shop. You may also want to display a photo of yourself and/or your employees and partners (make sure you get their permission in advance). If you include your business' history in the About page, photos from the past (most likely scanned) can make the information more interesting. When using your own images, make sure you optimize them for the web (e.g. trim white space, reduce picture dimensions, set JPEG quality to 80%).

Stock photos
It gets a bit tricky if you want to use stock photos. The basic rule is: do not copy photos from other sites (or link to them) unless you are absolutely sure that you will not violate the copyright laws (in most cases, you would). Some website builders (such as Weebly) allow you to easily search for and embed images in your web pages. You can also buy stock photos from such sites as iStockPhoto or get some for free from stock.xchng. You can also search for free images at GettyImages, Flickr, Google, or Creative Commons. Just make sure that you follow the terms of use for the particular license type (i.e. don't forget to include attribution when needed).

Writing for the web
When you add text to a web page, keep in mind the following rules. First, remember that people do not read business websites; they scan them for keywords and click the very first link that vaguely resembles a match. Therefore, do not write a composition. Use lists, short phrases, and brief paragraphs. Eliminate all unnecessary words. After your first draft, see if you can reduce the amount of text by half. Do it. Then try reducing what is left by half again. When you write text for a web page, use the exact combinations of keywords that you expect your potential customers to search for. This will help you get better page ranking.

Layout
When it comes to the web page layout, the simpler, the better. Use a simple layout and simple content. Don't try to impress people with sophistication (unless this is the nature of your business). Keep it minimal, keep it simple. Limit styles to the minimum. You should use at most 3 font sizes (one for headings, one for paragraphs, one for small print) and two font faces (one for headings and another for everything else).

Getting better
If you are a novice building your very first website, here are some books that can help you get better. If you were to get just one book on the topic, I'd recommend Steve Krug's Don't Make Me Think: A Common Sense Approach to Web Usability (this is a short and entertaining book, which I finished in a couple of evenings). The Non-Designer's Design Book by Robin Williams is a good primer that will help you understand the basic design principles.

Final touches
Do not publish your website (to your custom domain) until it's ready. If you publish a half-baked site, you will be penalized by search engines. When working on your website, and especially when making lots of changes, leave it for a few days and then visit it again. Taking a break from your website will give you a better perspective and help you catch the problems with a fresh eye. Before publishing the site, show it to someone and ask for an honest feedback. It would be helpful to find someone with background in web design and/or web development, but even without it, having more people to check out your work will help you find the things that you have missed. Also, make sure that you check the following:

Verify that the site works in all major web browsers (Internet Explorer, Chrome, Firefox, Safari).

Test it using a smart phone and/or a portable/mobile device, such as a tablet.

Inspect all content: text (make sure there are no error or typos), images, links (click on every link to see if it points to the right location), downloads (if you host any files, such as PDF documents).

Once you have reviewed and tested your website, you should be ready to publish it.